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The branched structures of dendronized polymers can provide good steric stabilization for metal nanoparticle catalysts. In this work, an amphiphilic dendronized copolymer containing hydrophilic branched triethylene glycol moieties and hydrophobic branched ferrocenyl moieties is designed and prepared by one-pot ring-opening metathesis polymerization, and is used as the stabilizer for metal (Au, Ag and Pd) nanoparticles. These metal nanoparticles (Au nanoparticles: 3.5 ± 3.0 nm; Ag nanoparticles: 7.2 ± 4.0 nm; Pd nanoparticles: 2.5 ± 1.0 nm) are found to be highly active in both the 4-nitrophenol reduction and Suzuki–Miyaura reactions. In the 4-nitrophenol reduction, Pd nanoparticles have the highest catalytic ability (TOF: 2060 h−1). In addition, Pd nanoparticles are also an efficient catalyst for Suzuki–Miyaura reactions (TOF: 1980 h−1) and possess good applicability for diverse substrates. The amphiphilic dendronized copolymer will open a new door for the development of efficient metal nanoparticle catalysts. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical features, dendronized polymers (DPs) have received increasing attention in various fields such as hierarchically structured materials, stimuli-responsive materials, catalysis, biosciences, optoelectronic devices, and so on. A large number of synthetic strategies also have been reported to prepare various functionalized DPs. Among these strategies, ring-opening metathesis polymerization (ROMP) and metathesis cyclopolymerization (MCP) using highly active and group-tolerant Ru-based catalysts as initiators were used as living and controlled techniques to fabricate well-defined DPs. The two efficient techniques present a promising prospect in the design and preparation of functional DPs. In this review, we focus on the synthesis of various classes of DPs by ROMP and MCP of dendritic macromonomers, and describe their characteristic structures and properties, as well as various functional applications. [ABSTRACT FROM AUTHOR]

Dendronized polymers (DPs) are an increasing field at the interfaces between organic chemistry, polymer synthesis, and materials science, and in particular DPs are expected to provide designed applications as nanoparticle (NP) sensors and catalysts. Herein, we report a new highly-branched amphiphilic dendronized diblock copolymer containing bulky hydrophilic triethylene glycol (TEG) and hydrophobic ferrocenyl (Fc) groups via the living and controlled ring-opening metathesis polymerization. The amphiphilicity drives the self-assembly of the resulting DP into spherical nanoscale micelles in water using THF or DMSO as cosolvents. AuNPs and AgNPs of various sizes depending on the presence of NaBH 4 are successfully prepared using the DP as stabilizers or reductants and used as excellent catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol by NaBH 4. The obtained AuNPs about 2.1 nm show TONs up to 25 000 and TOFs of 26 400 h−1 and remain stable and efficient for this catalysis after two months. Highly-branched amphiphilic ferrocenyl-containing dendronized diblock copolymer is prepared by ROMP and used as stabilizers or reductants to synthesize AuNPs and AgNPs for high-efficiency catalysis in 4-nitrophenol reduction. Image 1 • Ferrocenyl dendronized diblock copolymer is synthesized by ROMP. • Dendronized copolymer can self-assemble into nanoscale spherical micelles. • Dendronized copolymer can be used as reducing and stabilizing agents for AuNPs/AgNPs. • AuNPs and AgNPs show high catalytic activity for 4-nitrophenol reduction. • AuNPs and AgNPs show long-term stability and efficiency for catalysis. [ABSTRACT FROM AUTHOR]

Metal nanoparticle composite hydrogels (MNCHs) have attracted considerable attention in the catalytic field because hydrogels can provide appropriate microenvironment and enable catalysts to be conveniently separated and recycled. Here, a novel and well-defined gallol-functionalized hydrogel Gel-G was synthesized by ring-opening metathesis polymerization (ROMP). The resulting hydrogel Gel-G can be used as template to in situ prepare catalytically active gold nanoparticles hydrogel (AuNPs-Gel-G) and sliver nanoparticles hydrogel (AgNPs-Gel-G) without use of any external reductant based on the strong reducibility and coating property of the gallol moiety. The two MNCHs were well characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Both AuNPs-Gel-G and AgNPs-Gel-G exhibited high catalytic activity for the 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP), and can be easily separated and reused at least five times. [Display omitted] • Gallol-containing polymer hydrogels are synthesized by ROMP. • Gallol-containing polymer hydrogels are used for in situ fabrication of AuNPs and AgNPs composites. • AuNPs and AgNPs hydrogel composites exhibit good catalytic activity and reusability for 4-nitrophenol reduction. [ABSTRACT FROM AUTHOR]

Due to their high catalytic activity, gold nanoparticles (AuNPs) have been exploited as green and efficient catalysts in various chemical reactions, such as the oxidation of CO to CO 2 , aerobic oxidation of alcohols, C C coupling reactions and reduction reactions through transfer hydrogenation. Here, we report an efficient dendritic stabilizer for AuNPs. The dendritic stabilizer is a ferrocene-containing amphiphilic dendronized random copolymer that is synthesized by the ring-opening metathesis polymerization. And, the obtained amphiphilic copolymer can self-assemble into spherical micelles in aqueous solution, resulting in the formation of efficient nanoreactors for AuNPs in the 4-nitrophenol reduction to 4-aminophenol by NaBH 4. It is found that AuNPs obtained by using NaBH 4 as reductant have obviously smaller size and higher catalytic activity than those fabricated by using the ferrocene-based groups as reductant. The reusable experiment indicates that the small-sized AuNPs can be reused at least for fifteen times. We report ferrocene-containing amphiphilic dendronized random copolymer as efficient stabilizer for reusable gold nanoparticles in the reduction of 4-nitrophenol. Unlabelled Image [ABSTRACT FROM AUTHOR]

Hydrogels with stimuli-responsive behavior have been of great interest to researchers from many fields, such as biotechnology, drug delivery, and sensors, owing to their "smart" change in properties under external stimuli such as temperature, pH, pressure, redox, magnetic and electric fields. In this work, using the third generation Grubbs' catalyst as the initiator, both temperature and β-cyclodextrin (β-CD) stimuli-responsive ferrocenyl hydrogels were prepared with different proportions of hydrophilic norbornene monomer NTEG , ferrocene-containing monomer NFc and crosslinker 1 by using one-pot ROMP (ring-opening metathesis polymerization) reaction. Based on the mechanical and rheological tests, it was found that NFc not only played a crucial role in maintaining the structure of ferrocenyl hydrogels, but also enhanced their physical strength. Comparatively, the increase of the NTEG content in the hydrogel system can improve the toughness of the resulting hydrogels. Furthermore, Results of the swelling ratio test demonstrated that these hydrogels possessed temperature-responsiveness, in which the NTEG block, which contained dendritic oligoethylene glycol structures in the side chain, played a decisive role. Simultaneously, it is worth noting that these ferrocenyl hydrogels also exhibited responsive behavior to β-CD solution due to the host-guest interaction of ferrocene unit with β-CD macromolecule. Therefore, we believe that this study provides a new idea for the design of covalently crosslinked ferrocenyl stimuli-responsive smart hydrogels. Thermo/β-cyclodextrin-responsive ferrocenyl hydrogels were constructed by the ROMP reaction of a hydrophilic norbornene monomer containing dendritic oligoethylene glycol structures in the side chain and a hydrophobic side-chain ferrocene-containing monomer, and their mechanical and swelling properties could regulated by the hydrophilic-hydrophobic ratio, environmental temperature and the addition of β-cyclodextrin. [Display omitted] • Hydrogels with pendent ferrocene and dendritic oligoethylene glycol were prepared. • Ferrocenyl hydrogels were covalently cross-linked through the ROMP reaction. • Ferrocenyl hydrogels had excellent toughness and compression resilience. • Mechanical/swelling behavior of hydrogels can be regulated by changing feed ratio. • Ferrocenyl hydrogels possessed dual-responsiveness to temperature and β-CD. [ABSTRACT FROM AUTHOR]

The development of novel polymer carriers, which have well-defined structures and desired conjugative abiltiy to therapeutic agents, is still an urgent requirement in the field of polymer–drug conjugates (PDCs) used for stimuli-responsive drug delivery systems. Herein, we present the controlled synthesis of a novel amphiphilic polynorbornene-based block copolymer, side-chain containing hydrophobic functionalizable benzaldehyde groups and hydrophilic dentritic triethylene glycol (TEG) moieties, by the ring-opening metathesis polymerization (ROMP) using the 3rd generation Grubbs catalyst 1 as the initiator. The obtained copolymer can self-assemble into spherical micelles with the average size of 84 nm in water, and its remarkable ability as the polymer carrier to fabricate PDCs was fully confirmed by the efficient covalently Schiff-base linking of its side-chain benzaldehyde groups to amino groups of model drugs including O-benzylhydroxylamine (BHA), 1-hexadecanamine, tryptophan and benzocaine. Notably, torispherical micelles with the average size of 90 nm were also obtained by the self-assembly of the formed polymer-BHA conjugate, and the pH-triggered release of BHA molecules from the micelles was observed at acidic environments (for example, pH 4.0 and 2.5). Therefore, the present polynorbornene block copolymer is expected to find potential applications in the stimuli-responsive drug delivery systems as a promising polymer carrier to form PDCs via acid-responsive Schiff-base linkage with amino-containing drugs such as doxorubicin, daunorubicin, epirubicin and pirarubicin. [ABSTRACT FROM AUTHOR]